Outline and Prospects of SAFOD Project

SAFOD is a project to investigate and understand the rupture process of the San Andreas Fault through an investigation of material composition of the fault zone; observation to reveal underground structure; and measurement of physical properties, such as stresses on and around the fault, permeability, and pore pressure, etc. at Parkfield. In addition to observation by a seismometer and tilt-meter which were installed at a depth of about three kilometers in a borehole in the fault zone, core sampling and geophysical logging were carried out as part of this project. High quality data, such as that on guided waves (special seismic waves that propagate in the fault zone) and repeated earthquakes (earthquakes with very similar waveforms) were acquired. Such data can be very useful in understanding the fault rupture process. (authors)